Update pollard-rho.cpp

Author: hsnavarro

math/pollard-rho.cpp

@@ -7,10 +7,10 @@ ll pollard(ll n) {
   while (1) {
     y = x = 2;
     while (1) {
-      x = mulmod(x,x,n); x = (x-c)%n;
-      y = mulmod(y,y,n); y = (y-c)%n;
-      y = mulmod(y,y,n); y = (y-c)%n;
-      d = gcd(abs(n+y-x), n);
+      x = addmod(mulmod(x,x,n), c, n);
+      y = addmod(mulmod(y,y,n), c, n);
+      y = addmod(mulmod(y,y,n), c, n);
+      d = gcd(abs(x-y), n);
       if (d == n) break;
       else if (d > 1) return d;
     }